This invention relates to display racks, furniture and like structures formed with elongated tubes of square cross-section, and more particularly, to connectors for the ends of the square tubes used in such structures.
An object of the invention is to provide an effective connector for establishing a secure relationship with the end of a tube, or with the ends of two or more tubes.
Another object of the invention is to provide such a connector that can be manufactured at low cost.
Still another object is to provide a connector that is easy to install, and which avoids the use of screws, clips or friction fits which usually require pounding.
Yet another object is to provide a connector suitable for use with square cross-section tubes of either mill run (premium) grade or tubes of commercial (off the shelf) grade. The latter are available in smaller quantity and at lesser cost than the mill run grade.
Applicant believes he is familiar with commercially available connectors for tubes of square cross-section, and he represents that he never has encountered a connector constructed in accordance with this invention. Among the connectors on the market are those relying on a friction fit which must be forced (pounded) into an associated tube. Such connectors are subject to loosening under conditions of vibration, and are difficult to disassemble. Other prior connectors have a screw threaded in the connector which following assembly with a tube are backed into an accurately located opening in the tube. Other connectors use clips, separate wedge members and separate resilient members for establishing connections with associated tubes.
Prior art patents disclosing connector devices of the same general class as subject development are Italian Pat. No. 530,415 bearing dates of 1954, 1955 and 1957, and the following U.S. Pat. Nos.:
2,926,941 PA1 3,155,405 PA1 3,211,481 PA1 3,218,097 PA1 3,255,721 PA1 3,314,699